The present invention relates to a technique of manufacturing a semiconductor device. In particular, the present invention relates to a sample releasing method and a plasma processing apparatus suitable for manufacturing the semiconductor device.
Plasma etching is known as one of a plasma processing method in manufacturing the semiconductor device. In the plasma etching, a sample substrate (wafer) is arranged on a sample stage in a processing chamber and is exposed to plasma. At this time, a specific laminated film is selectively removed on the wafer by adjusting various processing conditions such as a kind of gas introduced into the processing chamber, and radio frequency power applied to the wafer, and a fine circuit pattern is formed on the wafer.
In the plasma etching described above, the wafer is generally fixed onto the sample stage by using an electrostatic chuck electrode because of a demand for preventing a positional deviation of the wafer in processing or adjusting temperature of the wafer. After the processing, fixing of the wafer is cancelled, and the wafer is released from the sample stage by using releasing mechanism which pushes up the wafer toward above the sample stage, and then the wafer is conveyed from the processing chamber.
In chucking of the wafer by using the electrostatic chuck electrode, the wafer is attracted by electrostatic force generated in dielectric film arranged between an electrode and the wafer by applying voltage to the electrode. Accordingly, the chucking is cancelled by interrupting the voltage applied to the electrode, however electric charge is remained due to a lack of destaticization to the dielectric film or the wafer, and therefore the attraction force to the wafer may be maintained after interrupting the voltage to the electrode.
When the remaining attraction force is generated, the positional deviation of the wafer in releasing the wafer from the sample stage might be occurred, or the wafer might be fractured due to force applied to the wafer in releasing. The positional deviation of the wafer leads a device error in conveying of the wafer, and as a result, product processing might be stopped. The fracture of the wafer leads not only a loss of the wafer but also a loss of time for recovering of the device to remove the fractured wafer from the device. In each case, a product throughput might be deteriorated, and therefore it is necessary to reduce the remaining attraction force by means of the destaticization in order to reduce a chance of occurrence of the problem described above. The following method is known as a destaticization method to reduce the attraction force.
In JP-A-2010-040822, a destaticization method including a step of applying a chuck voltage to an electrostatic chuck electrode in an electrostatic chuck device and electrostatically attracting a processed substrate to the electrostatic chuck electrode, a step of processing the processed substrate in a state in which the processed substrate is electrostatically attracted to the electrostatic chuck electrode, a vacuum processing step of vacuuming a chamber after the step of processing to the processed substrate is finished, a step of stabilizing the voltage of the electrostatic chuck electrode in the same polarity voltage as the chuck voltage during the vacuum processing step, a step of providing a destaticization gas into the chamber after the voltage of the electrostatic chuck electrode is stabilized, a step of changing the destaticization gas, which is provided into the chamber, into plasma, a step of releasing the processed substrate from the electrostatic chuck electrode, and a step of setting the electrostatic chuck electrode to a reference potential after the processed substrate is released from the electrostatic chuck electrode, is disclosed.
Further, in JP-A-2004-047511, a releasing method which releases an attracted object, which is arranged on a dielectric body including an electrode therein and is attracted to the dielectric body by means of electrostatic force caused by applying DC voltage having a predetermined polarity to the electrode, from the dielectric body is disclosed. The releasing method includes a destaticization method including a step of stopping the application of the DC voltage to the electrode, a step of exposing the attracted object to plasma for destaticizing, and a voltage applying step in which the DC voltage having the same polarity as a self-bias voltage generated in the attracted object by exposing the attracted object to the plasma is applied to the electrode.